Japanese probe about to drop hopping robots onto asteroid Ryugu

A Japanese asteroid-sampling probe is about to get up close and personal with its target space rock.

The Hayabusa2 spacecraft will drop two tiny rovers onto the asteroid Ryugu this week, possibly as early as Thursday (Sept. 20), if all goes according to plan, Space.com reports.

The Hayabusa2 team began prepping seriously for the epic maneuver last week. The current schedule calls for the mother ship to descend toward Ryugu today (Sept. 19) and for the two little disk-shaped robots, known as MINERVA-II1A and MINERVA-II1B, to deploy as early as tomorrow, US time

Each MINERVA-II rover measures 7 inches wide by 2.8 inches tall (18 by 7 centimeters), with a mass of about 2.4 lbs. (1.1 kilogram). And they won't "rove" in the traditional sense; instead of rolling along on wheels like a Mars or moon explorer, the duo will hop from place to place on Ryugu.

"Gravity on the surface of Ryugu is very weak, so a rover propelled by normal wheels or crawlers would float upwards as soon as it started to move," Hayabusa2 team members wrote in a MINERVA-II1 description. "Therefore, this hopping mechanism was adopted for moving across the surface of such small celestial bodies. The rover is expected to remain in the air for up to 15 minutes after a single hop before landing, and to move up to 15 m [50 feet] horizontally."

The rovers will move autonomously, exploring multiple areas on the surface of the 3,000-foot-wide (950 meters) Ryugu, the update added. The duo will gather a variety of data with their science gear, which includes temperature sensors, optical sensors, accelerometers, gyroscopes and a total of seven cameras that are shared by the two rovers.

The upcoming touchdowns kick off an extended surface-exploration campaign for the $150 million Hayabusa2 mission, which launched in December 2014 and arrived in orbit around Ryugu on June 27 of this year. Hayabusa2 is scheduled to drop a larger lander called MASCOT onto the asteroid next month, and another little hopping rover, MINERVA-II2, next year.

And the Hayabusa2 mothership will make several forays of its own to the surface next year, grabbing Ryugu material each time. The orbiter will leave Ryugu in December 2019, and its samples will return to Earth in a special capsule a year later.

Each MINERVA-II rover measures 7 inches wide by 2.8 inches tall (18 by 7 centimeters), with a mass of about 2.4 lbs. (1.1 kilogram). And they won't "rove" in the traditional sense; instead of rolling along on wheels like a Mars or moon explorer, the duo will hop from place to place on Ryugu.

"Gravity on the surface of Ryugu is very weak, so a rover propelled by normal wheels or crawlers would float upwards as soon as it started to move," Hayabusa2 team members wrote in a MINERVA-II1 description. "Therefore, this hopping mechanism was adopted for moving across the surface of such small celestial bodies. The rover is expected to remain in the air for up to 15 minutes after a single hop before landing, and to move up to 15 m [50 feet] horizontally."

The rovers will move autonomously, exploring multiple areas on the surface of the 3,000-foot-wide (950 meters) Ryugu, the update added. The duo will gather a variety of data with their science gear, which includes temperature sensors, optical sensors, accelerometers, gyroscopes and a total of seven cameras that are shared by the two rovers.

The upcoming touchdowns kick off an extended surface-exploration campaign for the $150 million Hayabusa2 mission, which launched in December 2014 and arrived in orbit around Ryugu on June 27 of this year. Hayabusa2 is scheduled to drop a larger lander called MASCOT onto the asteroid next month, and another little hopping rover, MINERVA-II2, next year.

And the Hayabusa2 mothership will make several forays of its own to the surface next year, grabbing Ryugu material each time. The orbiter will leave Ryugu in December 2019, and its samples will return to Earth in a special capsule a year later.